HAZARDOUS AREAS - Comparisons Between Standards

The following tables and comments are an attempt to cross reference between different National standards for Hazardous Location Definitions. We note that there is a world wide trend towards IEC standards in the electrical industry and that even the American manufacturers are gearing up to produce products to IEC standards in IEC metric dimensions.


COMPARISON OF ZONES FOR ELECTRICAL EQUIPMENT

IEC/CENELEC/U.K.
GERMANY/JAPAN		 U.S.A.
ZONE 0 DIVISION 1
ZONE 1 DIVISION 1
ZONE 2 DIVISION 2

COMPARISON OF CLASS II CLASSIFICATIONS - DUSTS

B.S.6467 & A.S. 2236
-CLASS II		 U.S.A.-CLASS II
DIP - NO SUB - GROUP GROUP E - METAL DUSTS

 GROUP F - COAL DUSTS

 GROUP G - GRAIN DUSTS

COMPARISON OF GAS GROUPINGS FOR ELECTRICAL EQUIPMENT

IEC
CENELEC
AUSTRALIA		 U.KBS4683 GERMANY & JAPAN

VDEO171

RIIS-TR-TR-79-1

 U.S.A.
NATIONAL
ELECTRIC
CODE		 Representative Gases
II IIA II IIA 1 D Propane
IIB IIB 2 C Ethylene
IIB IIC 3n 3a B Hydrogen
IIB 3b None Carbon Disulphide
IIB 3c A Acetylene

COMPARISON OF ZONES FOR TEMPERATURE CLASSIFICATIONS FOR ELECTRICAL EQUIPMENT.

IEC/CENELEC
AUSTRALIA		 JAPAN
(RIIS - TR - 79 - 1)		 U.S.A.
(NEC 1984)		 MIN
IGNITION
TEMP
DEG C
Class Maximum Surface
Temp. deg.C.		 Class Maximum Surface
Temp. deg.C.		 Class Maximum Surface
Temp. deg.C.
T1 450 G1 360 T1 450 450
T2 300 G2 240 T2
T2A
T2B
T2C
2TD		 300
280
260
230
215		 300
280
260
230
215
T3 200 G3 160 T3
T3A
T3B
T3C		 200
180
165
160		 200
180
165
160
T4 135 G4 110 T4
T4A		 135
120		 135
120
T5 100 G5 80 T5 100 100
T6 85 G6 70 T6 85 85

The tables above are a compilation of information from various sources which we believe to be correct, however, we can accept no responsibility for any inaccuracies.


EXPLOSION PROOF VS FLAMEPROOF

Americans refer to “Explosion Proof”, while the UK and IEC refer to “Flameproof” motors or equipment. In IEC definitions this is an Ex d piece of equipment. Ex d equipment is designed to contain an internal explosion to escape between the “flamepaths”, but cool any flame in the hot gases so that no flames escape from the enclosure to ignite any external flammable gases - hence “Flameproof”.

Although Ex e equipment is designed to be used in a Zone 1 area it cannot be described as “Explosion Proof” or “Flameproof”, as it will not contain an explosion if one did occur. Ex e equipment is manufactured to an approved “Explosion Proof Technique”.


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